How do I resolve a HTTP 414 "Request URI too long" error?

Based on John's answer, I changed the GET request to a POST request. It works, without having to change the server configuration. So I went looking how to implement this. The following pages were helpful:

jQuery Ajax POST example with PHP (Note the sanitize posted data remark) and

http://www.openjs.com/articles/ajax_xmlhttp_using_post.php

Basically, the difference is that the GET request has the url and parameters in one string and then sends null:

http.open("GET", url+"?"+params, true);
http.send(null);

whereas the POST request sends the url and the parameters in separate commands:

http.open("POST", url, true);
http.send(params);

Here is a working example:

ajaxPOST.html:

<html>
<head>
<script type="text/javascript">
    function ajaxPOSTTest() {
        try {
            // Opera 8.0+, Firefox, Safari
            ajaxPOSTTestRequest = new XMLHttpRequest();
        } catch (e) {
            // Internet Explorer Browsers
            try {
                ajaxPOSTTestRequest = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
                try {
                    ajaxPOSTTestRequest = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (e) {
                    // Something went wrong
                    alert("Your browser broke!");
                    return false;
                }
            }
        }

        ajaxPOSTTestRequest.onreadystatechange = ajaxCalled_POSTTest;
        var url = "ajaxPOST.php";
        var params = "lorem=ipsum&name=binny";
        ajaxPOSTTestRequest.open("POST", url, true);
        ajaxPOSTTestRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        ajaxPOSTTestRequest.send(params);
    }

    //Create a function that will receive data sent from the server
    function ajaxCalled_POSTTest() {
        if (ajaxPOSTTestRequest.readyState == 4) {
            document.getElementById("output").innerHTML = ajaxPOSTTestRequest.responseText;
        }
    }
</script>

</head>
<body>
    <button onclick="ajaxPOSTTest()">ajax POST Test</button>
    <div id="output"></div>
</body>
</html>

ajaxPOST.php:

<?php

$lorem=$_POST['lorem'];
print $lorem.'<br>';

?>

I just sent over 12,000 characters without any problems.


Under Apache, the limit is a configurable value, LimitRequestLine. Change this value to something larger than its default of 8190 if you want to support a longer request URI. The value is in /etc/apache2/apache2.conf. If not, add a new line (LimitRequestLine 10000) under AccessFileName .htaccess.

However, note that if you're actually running into this limit, you are probably abusing GET to begin with. You should use POST to transmit this sort of data -- especially since you even concede that you're using it to update values. If you check the link above, you'll notice that Apache even says "Under normal conditions, the value should not be changed from the default."